With the growing popularity of the Internet and networks in general, there is a trend towards centralized network services, and centralized network service providers. To be profitable, however, network service providers need to constantly maintain and if possible expand their customer base and their profits. Since leased line services are coming under increased competition, profit margins have been decreasing for their providers. Thus, an increasing number of providers are trying to attract small and medium sized businesses by providing network with value added services and a centralized network management system. Network providers are offering VPNs to interconnect various customer sites that are geographically dispersed. VPNs are of great interest to both provider and to their customers because they offer privacy and cost efficiency through network infrastructure sharing.
Today, a virtual private network (VPN) virtually implementing, e.g., a company network on an IP (Internet Protocol) network is attracting increasing attention. Particularly, a MPLS-VPN using MPLS easily provides a VPN solution for supporting private addresses while securing customer data.
In general, customers of MPLS/VPN services desire that they are charged based on VPN site usage, instead of fixed monthly charges that are based on number of sites within VPN and other similar billing policies. Typically, MPLS based routers have capabilities to capture the traffic data at the interfaces. When an IP packet arrives at a MPLS/VPN service provider network, these IP packets are encapsulated with MPLS labels by the ingress router. These packets then traverse through the MPLS-VPN network to reach the egress router based on the traffic-engineering patterns configured in the core network. Such flow records are then captured at the egress interfaces by a Usage Mediation Subsystem and aggregated into Usage Data Records (UDRs), which can later be used for billing purposes based on traffic patterns.
The egress interface of the Provider Edge (PE) router from where the flow records are collected provides information about the “destination VPN site” and the “VPN” that the traffic belongs. However, using source customer edge (CE) IP or destination CE IP obtained from the UDRs; there are no straight forward ways to compute the source PE IP address and the source PE ingress interface information. Also, in a deployment of the MPLS/VPN network, explicit traffic engineering Label Switch Path (LSP) tunnels are not always created, which could provide information about the source PE router information for a flow record. However, such LSP tunnels are generally not available. In a true routed-domain network, extensive computation and the knowledge of how MPLS works is required to compute the source PE IP information for each packet exiting the MPLS network.
Current techniques to monitor traffic statistics capture both ingress and egress data flow at each interface. Also, these techniques are designed to capture both the ingress and egress traffic data at each interface configured as a site of a VPN. The flow record captured at each site is based on time to arrive at source/destination. This flow record capturing scheme can significantly affect performance of a router. In addition, they are very complex to implement in usage mediation applications. Generally, only egress flow record is captured at MPLS-VPN interface for accounting purposes. However, these techniques require capturing data associated with both ingress and egress flow records and can result in capturing duplicate records, which can significantly increase central processing unit (CPU) utilization of routers. Further, these techniques result in huge processing overheads in terms of correlating records. Furthermore, processing of such flow records from all sources may have to be performed centrally, which can require very high end servers.